Download Himalayan Balsam

HIMALAYAN BALSAM
Impatiens glandulifera
Invasive Plant Information Note
What is it?
Himalayan balsam (Impatiens glandulifera) is an invasive annual plant species which is native to the
foothills of the Pakistani and Indian Himalayas. It was first introduced to Europe in the mid-1800s as
an ornamental garden plant. Since then, it has escaped into the wild and is now present in most
parts of Ireland. Himalayan balsam is particularly frequent in damp soil areas such as along the
banks of watercourses and damp woodland. Please see link to its distribution across Ireland:
http://maps.biodiversityireland.ie/#/Home.
Fig. 1: Himalayan balsam © CABI
Fig. 2: Invading pasture land © CABI
Why should we be worried about it?
Himalayan balsam grows rapidly and spreads quickly. From seed it can grow up to 2.5 metres high in
a single season. It absorbs fertiliser and water intended for crops. Himalayan balsam seeds
germinate from March and develop rapidly over the growing season into dense upright stands.
These stands smother native plants and prevent them from establishing (See Fig. 2). The
combination of its high rate of reproduction and large size facilitates rapid colonisation. When the
plant dies back in autumn it can leave the ground bare and vulnerable to erosion. Himalayan balsam
can increase costs on farms due to loss of land and habitat, riverbank erosion, increased flood risk
and loss of amenity.
Fig. 3: Explosive seed dispersal
Fig. 4: Himalayan balsam flower
(www.fineartamerica.com)
(www.paulrobson.co.uk)
How do we recognise Himalayan balsam?
The seedlings of Himalayan balsam begin to emerge as early as March. The stems are pinkish-red,
brittle and hollow with side branches originating from joints in the stem (See Fig. 5). Its stems are
translucent and succulent. The leaves of the Himalayan balsam are dark green, lance-shaped and
have sharply serrated edges. Leaves are 5-18cm long and range in width from 3-7cm (See Fig. 6).
Himalayan balsam flowers can vary between white, pink and purple, with colouration differing
among individuals within the same habitat. Each flower has 5 petals and is said to look like an
English policeman’s helmet (See Fig. 1 & Fig. 4). The fruit capsules are green and contain many
spherical seeds (which may be green or brown), eventually becoming black when they are mature.
Flowering commences by June and extends into October. Over the winter, the mature Himalayan
balsam plants rot and decay.
Fig. 5: Himalayan balsam stem
Fig. 6: Himalayan balsam foliage
Fig. 7: Shallow root system
(www.gobotany.newenglandwild.org)
(www.bcinvasives.ca)
(www.shim.bc.ca)
How does Himalayan balsam spread?
Himalayan balsam produces up to 2,500 seeds per plant. These seeds are released explosively from
capsules when disturbed (See Fig. 3). The seeds can be propelled up to 7 metres from the mother
plant. The seeds can remain viable for up to 18 months and are readily dispersed by wind or in
water.
How to manage Himalayan balsam
Complete eradication of Himalayan balsam from a site may take a number of years. Non-chemical,
chemical or a combination of both can be employed to remove the species. Grazing is an effective
non-chemical control for Himalayan balsam. Grazing and trampling by livestock can be introduced
from early May when plants are tender and sweet. Hand-pulling alone can also be employed if
grazing is not an option. Himalayan balsam has a shallow root system so is easy to uproot (See Fig.
7). Care should be taken to remove the whole plant. This form of control should ideally happen in
June, when the plants have grown to a good height, but have not yet flowered. Hand pulling may
require a follow-up in August due to new seeds sprouting. Vegetative material can be disposed of by
composting unless seeds are present, in which case the material should be disposed of by ‘deep
burial.’
For Further Information please visit:
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Invasive Species Ireland http://invasivespeciesireland.com/
European Commission http://ec.europa.eu/environment/nature/invasivealien/index_en.htm